Employing different signal thresholds based on type of information transmitted

ABSTRACT

A method is disclosed for determining whether to transmit from a first unit to a second unit, where the transmission is one of a first type and a second type. In the method, a signal from the second unit is received at the first unit, and the strength of the signal as received at the first unit is measured. A determination is made of whether the transmission is of the first type or the second type, and a first threshold is selected if the transmission is of the first type, or else a second threshold is selected if the transmission is of the second type. The measured signal strength is then compared to the selected threshold, and the transmission proceeds only if the measured signal strength exceeds the selected threshold.

FIELD OF THE INVENTION

The present invention relates to a method for transmitting informationfrom a transmission site to a receiving unit. More particularly, thepresent invention relates to such a method for deciding whether totransmit the information, wherein the receiving unit is a two-way unitthat sends a signal to the site, and wherein the decision to transmit isbased on a comparison of the strength of the signal as received at thesite against a signal threshold that differs based on the type ofinformation that is to be transmitted.

BACKGROUND OF THE INVENTION

In many transmission systems, a decision on whether to transmitinformation from a transmission site to a receiving unit is made basedon whether the receiving unit will likely actually receive theinformation to be transmitted. In at least some of such transmissionsystems, the receiving unit is a two-way unit that can receive the senttransmission from the transmission site and that can also send signalsback to the transmission site.

In such transmission systems, one way of deciding whether to transmitthe information is to have the receiving unit send a signal to thetransmission site, to then examine the strength of such sent signal asreceived at the transmission site, and to then make a judgment of theability of the receiving unit to receive the transmitted informationbased on such signal strength. That is, the ability of the receivingunit to receive the transmitted information from the transmission sitemay be related, at least roughly, to the strength of a sent signal asreceived from such receiving unit at such transmission site. Moreparticularly, if the signal strength is relatively strong, it is verylikely that the receiving unit can receive the transmitted information.Correspondingly, if the signal strength is relatively weak, it is verylikely that the receiving unit cannot receive the transmittedinformation.

One transmission system where such a decision is made is a cellulartelephone system. In such a cellular telephone system, a mobile/cellularphone is a radio transceiver that is coupled to a cellular switch by wayof a particular cellular tower that is also a radio transceiver, and thephone and the tower transmit to and receive from each other overpre-defined radio frequencies.

In such cellular telephone system, for example, a decision is madewhether voice communications can commence between the tower and thephone based on the strength of a signal sent from the phone and receivedat the tower. Such signal strength as received at the tower, typicallyexpressed in terms of decibels, is compared to a pre-defined signalstrength threshold, also typically expressed in decibels, to determinewhether the aforementioned voice communications can commence. Moreparticularly, if the signal strength is stronger than the threshold, itis very likely that the phone can receive the voice communications fromthe tower, and communications may commence. Correspondingly, if thesignal strength is weaker than the threshold, it is very likely that thephone cannot receive the voice communications from the tower, andcommunications may not commence.

As may be appreciated, the aforementioned cellular telephone system isexpanding to include many additional services over and above mere voicecommunications. In particular, one additional service is datacommunications, wherein textual/ASCII messages are delivered to aparticular cellular telephone for display on a display associated withsuch cellular phone. The display may be any appropriate display, but istypically a pixelated display such as an LCD screen on the surface ofthe cellular phone. Thus, a message is composed and sent from anappropriate source, is transmitted to the cellular phone by way of thecellular telephone system, and is then displayed by the cellular phoneon the display associated therewith.

As with the decision on whether voice communications can commence, thedecision on whether to transmit the message data from the tower to thephone is made based on the strength of a signal sent from the phone andreceived at the tower. More particularly, if the signal strength isabove a pre-defined threshold, it is very likely that the phone canreceive the message data from the tower, and transmission thereof maycommence. Correspondingly, if the signal strength is below thepre-defined threshold, it is very likely that the phone cannot receivethe message data from the tower, and transmission thereof may notcommence.

An issue arises in that a typical cellular phone can reliably receivemessage data even under conditions where voice communications areinadvisable. That is, conditions may exist (1) where both voicecommunications and message data reception are advisable, (2) where onlymessage data reception is advisable, or (3) where neither voicecommunications nor message data reception is advisable. Nevertheless,when determining whether voice communications can commence and also whendetermining whether message data transmission can commence, theaforementioned cellular system compares signal strength to only a singlepre-defined threshold, where such threshold is calibrated for voicecommunications. As a result, message data transmission does not occurunder condition (2), above, even though such message data transmissionis in fact advisable.

Accordingly, a need exists for a method for deciding whether to transmitmessage data and for deciding whether voice communications can commence,wherein such decision is based at least in part on one threshold formessage data transmission and another threshold for voicecommunications.

SUMMARY OF THE INVENTION

The present invention satisfies the aforementioned need by providing amethod for determining whether to transmit from a first unit to a secondunit, where the transmission is one of a first type and a second type.In the method, a signal from the second unit is received at the firstunit, and the strength of the signal as received at the first unit ismeasured. A determination is made of whether the transmission is of thefirst type or the second type, and a first threshold is selected if thetransmission is of the first type, or else a second threshold isselected if the transmission is of the second type. The measured signalstrength is then compared to the selected threshold, and thetransmission proceeds only if the measured signal strength exceeds theselected threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary as well as the following detailed description ofthe present invention will be better understood when read in conjunctionwith the appended drawings. For the purpose of the illustrating theinvention, there are shown in the drawings embodiments which arepresently preferred. As should be understood, however, the invention isnot limited to the precise arrangements and instrumentalities shown. Inthe drawings:

FIG. 1 is a diagrammatic view and shows a typical cellular telephonesystem such as that which would employ the method of the presentinvention; and

FIG. 2 is a flow chart showing steps performed in selecting a thresholdin accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Certain terminology may be used in the following description forconvenience only and is not considered to be limiting. For example, thewords “left”, “right”, “upper”, and “lower” designate directions in thedrawings to which reference is made. Likewise, the words “inwardly” and“outwardly” are directions toward and away from, respectively, thegeometric center of the referenced object. The terminology includes thewords above specifically mentioned, derivatives thereof, and words ofsimilar import.

Referring to the drawings in detail, wherein like numerals are used toindicate like elements throughout, there is shown in FIG. 1 a typicalcellular telephone system 10 in accordance with one embodiment of thepresent invention. As seen, the system 10 includes one or more mobileswitching centers 12, one or more radio transceiver cellular towers 14,and one or more cellular telephones 16. As is known, each tower 14 isassociated with a particular switching center 12, and, depending on thelocation of a particular telephone 16, such phone 16 registers to one ofthe towers 14 and therefore is switched through the associated switchingcenter 12. Thus, voice communication between the phone 16 and the restof the world is achieved through the registered tower 14 and theassociated switching center 12, and data transmission that originatesfrom the world for the phone 16 is routed to the associated switchingcenter 12 for further transmission to the registered tower 14 and thento the phone 16.

Note that each tower 14 need not necessarily be an actual tower.Instead, the functional elements of a tower 14 may reside on the top orside of a building, on a mountain or mountainside, or in any otherappropriate location, all without departing from the spirit and scope ofthe present invention. Such functional elements may even be positionedon the ground or on a floating platform at sea, if appropriate asdictated by circumstances and terrain, for example.

Such a cellular telephone system 10 is generally known to the relevantpublic, and therefore need not be described in any greater detail exceptto the extent so indicated below. Although the present invention asdisclosed herein is described in terms of such a cellular telephonesystem 10, it is to be recognized that the present invention may also beemployed in connection with other systems without departing from thespirit and scope of the present invention. For example, such othersystem may be any wireless or wired system, any audio, video, and/ordata transmission system, etc.

Typically, and as seen in FIG. 2, when a phone 16 is first powered on(step 201), the phone 16 scans for acceptable control channels 18 astransmitted from the towers 14 (step 203), and then selects one of theacceptable control channels (step 205). As may be appreciated, eachtower 14 transmits at least one control channel 18, and each acceptablecontrol channel 18 may have a minimum signal strength, for example.Likewise, the selected control channel 18 may be the strongest one ofthe acceptable control channels 18 detected by the phone 16, thusindicating that the corresponding tower 14 is closest to the phone 16.Of course, other bases may be employed for selecting an acceptablecontrol channel 18 without departing from the spirit and scope of thepresent invention.

As may also be appreciated, the selected control channel 18 includesinformation readable by the phone 16, including but not limited tofrequency information for transmitting to and receiving from thecorresponding tower 14. Thus, the phone 16 reads such controlinformation from the control channel 18 (step 207) and uses such controlinformation to contact and register with the corresponding tower 14 andassociated switching center 12 (step 209). Thus, the world can contactthe phone 16 and the phone 16 can also contact the world through suchtower 14 and switching center 12.

In the present invention, the switching center 12 may decide to contactthe phone 16 by way of the tower because such switching center 12 isattempting to establish voice communications between such phone 16 and acalling party, because such switching center 12 is attempting to sendmessage data from a message source to the phone 16, because suchswitching center 12 is attempting to perform another type ofcommunication with the phone 16, or because of another reason.Accordingly, the switching center 12 sends a page to the phone by way ofthe tower 14 (step 211). As is to be appreciated, such page is sent overa frequency as set forth by the control information on the controlchannel 18, and the phone 16 is expected to be monitoring such frequencyif in fact such phone 16 is still powered on, still within range of thetower 14, and still registered to such tower 14. The phone 16, uponreceiving the page (step 213), transmits an acknowledgment of the pageto the switching center 12 by way of the tower 14 (step 215). Similar tothe page, such acknowledgment is sent over a frequency as set forth bythe control information on the control channel 18, and the tower 14 isexpected to be monitoring such frequency for such acknowledgment.

When such acknowledgment is received at the tower 14 (step 217), thestrength of the acknowledgment signal as received at the tower 14 ismeasured (step 219). Such strength is typically measured in decibels,although other measurement parameters/units may also be employed withoutdeparting from the spirit and scope of the present invention. As wasdiscussed above, once measured, the signal strength is then examined inorder to make a judgment of the ability of the phone 16 to commencevoice communications or receive message data based on such signalstrength. That is, the ability of the phone 16 to receive the messagedata or commence voice communications may be related, at least roughly,to the signal strength of the acknowledgment as received from such phone16 at such tower 14. As was pointed out above, such signal strength mustbe above a minimum threshold value.

As was also pointed out above, a typical cellular phone 16 can reliablyreceive message data even under conditions where voice communicationsare inadvisable. That is, conditions may exist (1) where both voicecommunications and message data reception are advisable, (2) where onlymessage data reception is advisable, or (3) where neither voicecommunications nor message data reception is advisable. This isparticularly true when the message data is simple digitized ASCII dataor the like, although other types of message data may be employedwithout departing from the spirit and scope of the present invention.However, when determining whether voice communications can commence andalso when determining whether message data transmission can commence,previous comparisons of signal strength were performed with regard toonly a single pre-defined threshold calibrated for voice communications.As a result, message data transmission did not occur under condition (2)even though such message data transmission was in fact advisable.

Accordingly, in one embodiment of the present invention, thedetermination of whether voice communications can commence is made withregard to a voice threshold, and the determination of whether messagedata transmission can commence is done with regard to a messagethreshold different from the voice threshold. The voice threshold anddata threshold may be any appropriate thresholds without departing fromthe spirit and scope of the present invention, although it is expectedthat the voice threshold will be higher than the data threshold. As aresult, message data transmission does in fact occur under condition (2)even though voice communication is not advisable. In one embodiment ofthe present invention, the voice threshold is about −95 to −90 dBm,while the data threshold is about −105 to −103 dBm.

In particular, and still referring to FIG. 2, the examination of themeasured signal strength of the acknowledgment signal begins with adetermination of whether voice communications is to commence or messagedata transmission is to commence (step 221). As should be appreciated,the switching center 12 already possesses such information inasmuch asthe switching center 12 originally sent the page to the phone 16 by wayof the tower 14 (step 211) because it had a voice communication or datatransmission for such phone 16.

Once the determination of voice communication or data transmission hasbeen made, an appropriate signal threshold is selected (step 223 a, 223b). As should be appreciated, in the case of a voice communication, thevoice threshold is obtained, and in the case of a data transmission, thedata threshold is obtained. Thereafter, the signal strength of theacknowledgement signal from the phone 14 as obtained at the tower 14 iscompared to the selected voice threshold or data threshold (step 225),and voice communication or data transmission, as the case may be, isallowed to commence only if the signal strength exceeds the selectedthreshold (step 227).

Note that, with regard to the message data transmitted, any appropriatedata transmission protocol may be employed without departing from thespirit and scope of the present invention. For example, in oneembodiment of the present invention, the SMS (Short Message Service)protocol is employed. Such SMS protocol is defined within the GSM(Global System for Mobile Communications) digital mobile phone standard.As was mentioned above, the transmitted data, once received by the phone16, is then displayed on a display 20 associated with such phone 16. Thedisplay 16 may be any appropriate display, but is typically a pixelateddisplay such as an LCD screen on the surface of the phone 16. Thus, amessage is composed and sent from an appropriate source, is transmittedto the phone 16 by way of the cellular telephone system 10, and is thendisplayed by the phone 16 on the display 20 associated therewith. Thedetails of such message composure, transmission, reception, and displayare generally know to the relevant public, and therefore need not bedescribed in any greater detail.

As should be understood, the method of transmitting information andchoosing a threshold as embodied in the present invention may beemployed by the switching center 12 or by another element withoutdeparting from the spirit and scope of the present invention. Moreover,although the method has been heretofore described in terms of onethreshold for voice communications and another threshold for messagedata transmission, it is to be recognized that additional thresholds maybe employed for other types of communications.

Although not necessary, such method is likely embodied in the form ofcomputer programming that is automatically run. Such programming isrelatively straightforward and should be apparent to the relevantpublic, and therefore need not be described herein in any detail.Accordingly, any particular form of programming and programming languagemay be employed without departing from the spirit and scope of thepresent invention.

In the foregoing description, it can be seen that the present inventioncomprises a new and useful method for deciding whether to transmitmessage data and for deciding whether voice communications can commence,wherein such decision is based at least in part on one threshold formessage data transmission and another threshold for voicecommunications. It should be appreciated that changes could be made tothe embodiments described above without departing from the inventiveconcepts thereof. It should be understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as defined by the appended claims.

What is claimed is:
 1. A method for determining whether to transmit froma first unit to a second unit, the transmission being one of a firsttype and a second type, the method comprising: receiving a signal fromthe second unit at the first unit; measuring the strength of the signalas received at the first unit; determining whether the transmission isof the first type or the second type; selecting a first threshold if thetransmission is of the first type; selecting a second threshold if thetransmission is of the second type; comparing the measured signalstrength to the selected threshold; and proceeding with the transmissiononly if the measured signal strength exceeds the selected threshold. 2.The method of claim 1 wherein the transmission is one of a voicecommunication and message data transmission, the method comprising:determining whether the transmission is a voice communication or amessage data transmission; selecting a voice threshold if thetransmission is a voice communication; and selecting a data threshold ifthe transmission is a message data transmission.
 3. The method of claim2 comprising: selecting a voice threshold if the transmission is a voicecommunication; and selecting a data threshold lower than the voicethreshold if the transmission is a message data transmission.
 4. Themethod of claim 1 wherein the transmission is one of a first type, asecond type, or a third type, the method comprising: determining whetherthe transmission is of the first type, the second type, or the thirdtype; selecting a first threshold if the transmission is of the firsttype; selecting a second threshold if the transmission is of the secondtype; and selecting a third threshold if the transmission is of thethird type.
 5. The method of claim 1 for determining whether to transmitfrom a fixed unit to a mobile unit, the method comprising: receiving asignal from the mobile unit at the fixed unit; measuring the strength ofthe signal as received at the fixed unit.
 6. The method of claim 5 fordetermining whether to transmit from a radio tower to a portable radiotransceiver, the method comprising: receiving a signal from the portableradio transceiver at the radio tower; measuring the strength of thesignal as received at the radio tower.
 7. The method of claim 6 fordetermining whether to transmit from a cellular telephone system towerto a cellular telephone, the method comprising: receiving a signal fromthe telephone at the tower; measuring the strength of the signal asreceived at the tower.
 8. The method of claim 1 further comprisingsending a page from the first unit to the second unit, wherein receivinga signal from the second unit at the first unit comprises receiving anacknowledgment of the page at the first unit.